Treatment of light petroleum distillates



June 3, 19M.. A. LAZAR ETAL. 2,244,164

` TREATMENT OF LIGHT PETROLEUM DISTILLATES yOriginal, Filed March 31.1937 Patented June 3, 1941 'raEarMENr or maar PETROLEUM msrmnrEs Arthurmaar, Berkeley, and Thomas F. McCormick, Oakland, Calif., assigner-s toTide Water Associated Oil Company, San Francisco, Calif., a corporationof Delaware `Application March 31, 1937, Serial No. 134,020, which is adivision of application Serial No. 67,370, March 5, 1936. Divided andthis appli-v cation May 23, 1938, Seal N0. 209,597

(c1. 19e-sn 3 Claims.

This invention relates to the recovery of byproducts from the refiningof petroleum which have properties making them extremely valuaable foruses hereinafter described.

The principal object of. this invention is to treat light petroleumdistillates in such a manner that valuable by-products can be recoveredin additional to normal petroleum products, thus making petroleum anentirely new source'for the manufacture and recovery of a number `oforganic compounds.

Another object is to so treat petroleum distillates with selectivesolvents of various characteristics that a separation of componenthydrocarbons in a distillate, (whether derived from a cracking processor not) can be effectedwith minimum losses.

Another object is to so treat and separate impurities from a petroleumdistillate of definite boiling range that a motor fuel of low sulphurcontent and bhigh anti-knock value is obtained.

Another object is to provide an improved process for recoveringsulphonic acids from acid sludges, whether such sludges are derivedfromv the herein described treating steps or from other treatingprocesses.-

Another object is to provide an improved process for isolating groups ofaromatic hydrocarbons, or sulphonic acids derived therefrom.

Another object is to provide for the separation of a petroleumdistillate so that substantially pure saturated hydrocarbons (parailinesand naphthenes) and pure aromatic hydrocarbons can be recovered. 1

Further objects will become apparent 'as the irgention becomes morefully disclosed hereina er.

Certain mineral oil distillates, such as those produced from Californiacrudes, contain appreciable quantities of non-hydrocarbon impurities. Inreiining such distiliates, particularly those comprising the normalboiling point range of gasoline, petroleum spirits, and kerosene. it isfound that the presence of these non-hydrocar-v bons interferes to acertain extent with the usual treating methods applied on saiddistillates.

Chemically speaking these non-hydrocarbons consist of organic acids,such as naphthenic acids, phenols, and the like, sulphur compounds ofacidic nature like mercaptans and thiophenols,

lother sulphurl compounds, and nitrogen bases.

Since the organic acids and nitrogen bases are also attacked bysulphuric acid, which is the treating agent generally used for refiningpetroleum products, these compounds will consume a certain amount of thetreating agent before the acid could have effected any actionupon theundesirable hydrocarbons to be removed.

In addition it has often been found that distillates containing suchimpurities cause didiculties in subsequent processing. For example,

if the distillates containing said non-hydrocarbons are treatedwithliquid sulphur-dioxide-or other solvents according to the well-knownEdeleanu process, it has been found that salts of nitrogen bases andresinous deposits are formed in the treating equipment. The salt crustsrepresent reaction products of sulphurous and sulphuric acid withnitrogen bases mixed with resinous material, which has been formed bypolymerization of the phenols. Such deposits often are quite troublesomeand can be the cause of the emulsions inthe SO2 or other treatingprocess, or, when accumulated in large quantities can interfere withheat transfer in the exchangers and evaporators of the treating unit,

`or when accumulated in lines and pumps, can

interfere with the through-put of the plant.

It' is therefore an object of this invention to submit mineral oildistillates composed of a plurality of fractions to a number of treatingsteps in the proper sequence and thereby to split the fractions up insuch a manner that valuable organic products are obtained whichheretofore could not be obtained from mineral oils in any appreciablequantity.

Broadly speaking, the invention involves the treatment of a petroleumdistillate (cracked or uncracked) with 'specic reagents-in such sequenceof steps that such reagents, which cannot under usual conditionsexercise their function of selectivity, are enabled to be applied with'complete selectivity.

This will bebetter understood infor instance, the reactions of sulphuricacid with hydrocarbons is considered when a certain concentration ofsulphuric acid is ineffective to dissolve, or react with, unsaturatedandaromatic hydrocarbons, while other concentrations may be used toeiectively separate-unsaturated and aromatic hydrocarbons from saturatedhydrocarbons and from each other. action of sulphuric acid and ofsolvents such as liquid sulphur dioxide, benzol-sulphur dioxide, phenol,furfural, nitrobenzene, dichlorethylether, a mixture of propane andcresylic acid, and like solvents, or a combination of any of these sol'-vents with each other or with liquid SO2, for hydrocarbons andimpurities in hydrocarbons, is so utilized herein that a rened petroleumdistillate of improved qualities is obtained while pure hydrocarbons ofdefinite characteristics and pure by-products are made available forvaried uses in the arts.

More specifically, the invention is applicable to the treatment of apetroleum distillate of gasoline boiling range (whether cracked or not)to assure a highly refined motor fuel of low sulphur content and highanti-knock value.

Referringto the diagrammatic flow sheet of the drawing, a light rawdistillate obtained from California crude petroleum, such as thegasoline, kerosene, or petroleum spirits fractions thereof is theoriginal stock to be treated.

Such raw distillate may be, merely by way of illustration and not oflimitation, a selected cut In consequence, this selective v from a crudeoil within the boiling range of a u following physical characteristics:

Gravity A. P. I 50.7 Initial boiling point F 155 End point F 470 Sulphurper cent-- 0.12

Nitrogen do 0.08

Aniline point F 127 As before stated, it must be understood that stepsof the process are particularly applicable to any selected overheaddistillate from petro- -leum which ranges in volatility from the lightgasoline cuts right through the various boiling ranges of petroleumspirits, kerosene, gas oil, spindle oil, and spray oils down to heavyviscous lubricating oils and the treatment of a gasoline fraction isdescribed as being illustrative of a fuller range of operations whichwill include the recovery of a very superior motor fuel as well as otherincluded purified products.

The raw distillate, depending on its boiling range, is subjected to aseries of steps for therernoval of impurities and recovery of finishedproducts.

Preferably the raw distillate is first treated with a solution ofalkali, such as caustic soda solution of a concentration of about from15 B. to 30 B. which serves with proper agitation to combine with theorganic. acids in the distillate and to break up the combination betweenthe organic acids and nitrogen bases in the distillate whilepolymerizing certain unstable resinous compounds therein and the thusreacted caustic with absorbed material is removed from the distillate.

The distillate is then agitated with sufficient l to prepare thedistillates for solvent refining. In

commercial operation certain stocks may require the neutralization ofthe last traces of sulphuric a-cid with caustic soda or other alkaliesbefore solvent refining,

The thus withdrawn caustic solution may be acidified with fresh acidwhich serves to throwY the absorbed organic acids out of solution forrecovery as such, while the spent dilute acid may be causticized withfresh caustic soda solution tc throw out the nitrogenous bases forrecovery as such.

If separate recovery of the organic acids and nitrogenous bases is notdesired, the thus spent caustic solution and spent dilute acid may bemixed to effect mutual 'neutralization which yields two layers ofliquids, the upper layer comprising an oily mixture of the abstractedorganic acids and nitrogenous bases very valuable as a disinfectant oil,while the lower water layer represents substantially a. solution ofsodium sulphate.

In must bo understood that while the above do.

scribed removal of organic acids and nitrogenous bases is preferablydone as the first step of the proc-ess so that the remaining steps ofthe process may be more clearly illustrated and facilitated, suchremoval is not essential as a first step but may be performed as a laterstep as will be later more fully described.

The thus purified distillate is then subjected to treatment with a'solvent such as liquid sulphur dioxide, or any of .the other describedand well known selective solvents, in a well known manner to separatethe distillate into two portions or layers.

The upper layer is known las the raiiinate composed of the paraliine andnaphthene series of hydrocarbons and the lower layer (termed theextract) consists mainly of the olefine, dioleiine, and aromatic seriesof hydrocarbons together with a certain percentage of saturatedhydrocarbons of the parafne and naphthene series and certain sulphurcompounds.

The raiiinate comprising a puriiied motor fuel of definite boiling rangebut of relatively low anti-knock value may be then used as such afterthe usual removal, or neutralization, of contained SO2, but theinvention comprehends its blending with products later derived from theextract to form a finished motor fuel of satisfactory ignition anddetonation characteristics.

Depending on required uses, the extract after removal of SO2 therefrommay either be used as is or first subjected to treatments -in certainsteps to derive certain products or to leave a fraction of highanti-knock value to be added to said raffinate.

The extract of gasoline boiling range is rst treated with sulphuric acidof a concentration from HzSOi up to Ia fuming acid containing 20% S03,depending on the action desired on the extract, and all treatments ofthe distillate or extract with the reagents described and used hereinare preferably conducted for the fullest contact emciency as for.example in accordance with the method disclosedin a co-pendingapplication of Edwards and Stark, Serial No. 532,000 filed April 22,1931, the range of temperatures used therewith being regulated frombelow F. up as high as 80? F., Adepending on the solvent'or sulphonatingeffect required from the sulphuric acid.

If organic acids and nitrogenous baseshave already been removeci fromthe extract of definite boiling range, the extract will be contactedwith sulphuric acid of 90% concentration, or greater, insuch quantityand at such temperature as to leave an extract composed mainly ofhydrocar-v bons of a cyclic structure, .such as aromatlcs andhydroaromatics. y

The acid treated extract, as such, or fractions of the same have uniqueproperties which make them suitable as a varnish and lacquer diluent inplace of the commonly used coal tar diluents. It shows a highcompatibility for nitro-cellulose and synthetic resin solutions whichare used in the manufacture of lacquers and enamels. On account of itshigh solvency power for resins,

- gums, rubber and the like, it can also be used in place of the highpriced turpentine. fFurthermore, due to its aromatic nature it has ahigher afiinity for vapors of a low boiling range thanordinaryzpetroleum distillates and therefore can advantageously be usedas an absorption oil in vapor recovery plants of all kinds.

In contradistinction to SO2 extracts removed from distillates such ascracked distillates or pressure distillates, an extract derived asdescribed from straight run distillates shows entirely dierent behaviorduring treatment with sulphuric acid. Treating losses are relativelyinsignificant with straight run extracts in comparison to pressuredistillate extracts, and the products obtained by `the same degree oftreatment are much superior in quality to those obtained from pressuredistillate extracts. y

When a pressure distillate is treated with strong sulphuric acid (95% ormore) for the purpose of removing sulphur compounds the acid chemicallyattacks the unsaturated hydrocarbons A large perpresent in the crackeddistillate. centage of the sulphuricacid is therefore used up in thisreaction and not for the removal of sulphur compounds. This involves awell known conversion of valuable hydrocarbons, as can be seen from th'efollowing laboratory data on acid treatment of a typical Californiapressure distillate. 'I'his hydrocarbon conversioni involvespolymerization of lighter hydrocarbons to heavier hydrocarbons and toremove these undesirable polymers it is usually necessary to follow acidtreatment of the pressure distillate with neutralization andredistillation.

. When an acid treatment of a fraction from an SO2 extract obtained'from a California oil is compared with acid treatment of a Californiapressuredistillate derived from the same stock, there is a markeddifference in the chemical action and the properties on the finishedproduct resulting therefrom. Moderate quantities of sulphuric acid whichwould be used for desulphurization of a fraction from an SO:v extractdoes not appreciably attack thehydrocarbons present in the extractfraction. v

The following tabulation shows that the acid removes the sulphurcompounds almost conn pletely without attacking desirable hydrocarbonsof high anti-knock qualities.

Corporation, of July, 1930.

Pressure S()x distillate extract A'cid rate, lha/bbl. 98% acid 30 30Treating loss:

By acid absorption (sludge) 4. 7 3. 5 By polymerization 5.0 None Percentby volume, total 9. 7 3. 5

Properties After After After As is and redis- As is scid Awe' 'e' ltreat tilling treat distimng Gravity A. P. I- 52. 7 49. 3 52. 0 33.5 v34. 5 sulphur, percent o. a 0. c5 0.15 o. 6s 0.10 mangimi" CW Antiknoekvaiue- -15 4o -15 +14 +18 nossay' Aniline point, F 115 125 115 46 52Distilling range:

I. B. P 114 1% 120 280 285 150 186 164 316 315 230 288 235, 345 t347 306356 300 370 372 367 411 365 395 393 4m 500` 400 420 4% 444 530 440 434435 The antiknock values shown above are based on the Secondary standardof the Ethyl Gasoline The plus values signifythe tenths of cc.s of leadtetraethyl required per gallon to'make the standard equal the sample. enegative values signify the tenths of cc.s required per gallon for thesample t proportions to a raffinate or to straight run I gasoline, orpressure distillate fractions, to form the heavy ends of the distillingrange, the light ends being the aforesaid ramnate, gasoline, or pressuredistillate fractions, `for the purpose of obtaining a combinationfuel`which has high B. t. u. values combined with good anti-knockproperties and a satisfactory volatility.

The importance of this anti-knock function will be more appreciated whenit is considered that the higherboiling point fractions in an ordinarygasoline have higher aniline points than the lower boiling pointfractions, and tha-t the anti-knock value of its higher boilingfractions is lower than that of the lower boiling fractions.

'I he reverse of this occurs with fractions derived from the treatedextract inasmuch as with increasing boiling point the aniline pointdecreases and the anti-knock value increases since the miscibllity ofhydrocarbons with aniline is directly proportional to the anti-knockvalue of the hydrocarbons, and thus a very important balance 4in theVdistillation curveand thus makes n ideal .fuel for internal combustionengines.

In addition to the many functions already described the practicallycomplete removal of active sulphur compounds is desired during the acidtreatment of sulphur dioxide or other solin this manner have excellentstability and are particularly adapted for use by the paint, varnish,and lacquer industry where stability against light and weatheringis ofprimary importance and there is no tendency for corrosion due to theelimination of active sulphur compounds.

In order to obtain other products, if it is .not desired to use thetreated extract as above set forth, or as raw material for solvents, thewhole, or part, of the extract may be further 'treated with up to 100%or more of its volume with concentrated sulphuric acid (varying from 90%acid up to 20% fuming acid) under such oonditions of temperature thatall the aromatica in the extract are sulphonated and the remainder ofthe extract will consist of more saturated hydrocarbons (mainlynaphthenes and hydroaromatics) which, when neutralized, are especiallyvaluable as special petroleum spirits, thlnners. Stoddard solvent, orsimilar solvents in which extremely low sulphur content, or completefreedom from both active and less active sulphur compounds is required.Due to the naphthenic nature of this remainder it still retains ignitioncharacteristics similar to average motor fuels and therefore can be usedeither straight or in blends with such fuels.

If the extract has been treated in the first place with but a smallamount of concentrated sulphuric acid, for the production of solvents ormotor fuel not more than about 10 polmds of acid to the barrel, merelyfor partial sulphur reduction, the acid sludge therefrom may bediscarded,` but it it has been treated .with acid up to as high as 30pounds of acid per barrel of extract for further sulphur reduction, theacid sludge may contain a similar concentration of sulphonic acids as iscontained in the acid sludge resulting from treatment oi' the extractwith 100% of its volume of concentrated sulphuric acid, and thesucceeding steps are ,applicable thereto'.

Depending on the sulphur content ofthe extract the sulphuric acidtreatment may be carried out in one or more steps but preferably in atleast -two stages for the subsequent recovery of sulphonic acids,naphthenes, and pure aromatics. The initial puriilcation with strongacid is particularly necessary if the sulphur content of the extract ishigh, and mayrequire up to 30 pounds of sulphuric acid per barrel fordesu]- phurization purposes. The degree oi' sulphuric acid treatment inone or more stages will depend on the sulphur content of the extract andquality and purincation of solvents, motor fuel,

sulphonic acids, saturated oils. and other byproducts desired. In theacid treatment` with two or morestages the initial 'treatment removesthe more easily attacked substances such as nonhydrocarbons, di-olenes,etc. and the subsequent, treatments will start to actively sulphonatearomatics.

the acid sludges from the concentrated heavy acid treatment of upto 100%by volume or more of sulphuric acid is used. v

To definitely illustrate, we can treat a high sulphur extract with 30pounds per barrel of strong` acid in six treats of five pounds perbarrel each. The rstoneor two treats will yield sludges contaminatedwith the reaction products of non-hydrocarbons which may be discarded inorderto avoid contamination of sludges later derived. The remainingtreats yield sludges containing substantial quantities of sulphonicacids as the sulphuric acid treatment 'starts to attack the aromatichydrocarbons to an appreciable extent. I'hese sludges maybe a suitablesource of slightly contaminated sulphonic acids, al-

though more purified by-products are obtained particularly) pure,vsulphonic acids from acid sludges formed in later treatment.'

With acid sludges containing relatively high percentages of sulphonicacids, as described, novel steps are next used on said sludges for therecovery of sulphonic acids and pure aromatica and Isuch. steps areapplicable to any acid sludges containing sulphonated compounds whetherderived from the before described treatment or derived from any othersulphuric acid treatment of other hydrocarbons and shows greatimprovement over the usual and conventional methods of treating acidsludges. Y

In the usual method, the acid sludge consisting of sulphonic acids andsulphuric acid is neutralized with calcium hydroxide which converts allthe acids present into calcium salts, such as calcium sulphate andcalcium sulphonates, which mixture is washed with water to leach out thewater soluble sulphonates and leave the water in- 1 soluble calciumsulphate, and the sulphonates are then concentrated. This procedure isvery tedious from the above described treatments` may be mixed with avolume of water amounting to about one-third (1/3) ot the sulphuric acidused on the extract which, after agitation and settling, provides twolayers of liquids due to the salting out effect of the tree mineral acidon the free sulphonic acids. As a result, the mineral acid content ofthe upper layer is greatly reduced and the lower layer retains aminimumof organicl compounds. y.

In consequence the upper layer consists mainly of sulphonic acids andthe lower layer consists mainly of sulphuric acid of` a relatively lowdegree of concentration.

The lowerlayer may then be drawn off and distilled under such conditionsof temperature and pressure that'any traces of sulphonic acidscontained'therein will be split by heat to free the aromatichydrocarbons which can be carried off as an overhead vapor and condensed'to yield pure aromatics. The liquid remaining in the vstill consists ofdilute sulphuric acid which may 'hydrocarbons are completely eliminatedandonly 75 be concentrated and recovered in any well known manner foruse and is especially adapted for such recovery because of its purityand freedom ifz'lrlimlienitrogen basesearlier removed from the distherrecovered from the dilute sulphuric acid during concentration, thesulphur compounds and other impurities contained in the acid sludge areapparently destroyed during distillation =and concentration` because thearomatica recovered v during thesesteps are free of such impurities.

The upper sulphonic layer can be isolated for' further purlncation, ortreated by. a hydrolizing steam distillation to drive off the aromaticsas overhead which are'condensed and'may be mixed with the. aromaticsderived from the lower layer while the remainder of the upper layerconsists of dilute sulphuric acid which can be concen trated for use asdescribed for the remainder of the lower layer.

In theevent that the upper, or sulphonic, layer is permitted to standfor some time without distillation, it has been noted that there is atendency for the formation of crystals of pseudocumene sulphonic acidand such crystals may be readily separated from said sulphonic layer bya centrifuge prior to subjecting the remainder of the sulphonic layer tothe hydrolizing steam distillation before described. A

The aromatic hydrocarbons thus derived by the aforesaid treatments ofthe upper and lower layers are exceptionally pure and require only theusual neutralizing and'washing treatments prior to use and such purityis due to the prior treatment of the distillate for the removal oforganic acids which otherwise would contaminate the sulphonic layer andcause secondary reactions. It may readily be perceived, for instance,that if phenols were not thus removed they would be sulphonated alongwith the aromatica and then later reappear as contaminating substances 4in the resultant products.

At the same time it must be noted that wnue the described removaloforganic acids and nitrosense, such for instance as are found in the U.S.

Modifications and alternanons of treltment ofA the raw distillate arethose stated. t

For instance, while the treatment of/'a raw gasoline distillate has beendescribed to yield a finished motor fuel of high anti-knock value, ifthe raw distillate initially is of gasoline boiling range, or of anyother overlapping boiling range, the SO2 or other extract derivedtherefrom may be distilled to yield a light fraction within the providedin addition to gasoline boiling range and bottoms heavier than suchrange. Such bottoms can then be recovered asa dark liquid of highfluidity and penetrating power suitable for use -for the destruction ofplant life, or a so-called weed killer, as a fuel for certain types ofDiesel engines, a outback oil or solvent for asphalt, pitch, coke, heavyresidua, or due to its penetrating power and wetting ability, as aiiotation oil.

The light fraction may then be treated according to the described stepsfor the same uses as described.

It is'thus clear by the steps enumerated that the treatment of a rawdistillate may be so conducted that not only is the distillate recoveredin a pure state, but that every stepassures the recovery of products ofvalue which heretofore in most cases have been useful in only aminordegree. l

It is understood that in referring to the boiling or distillation -rangeof any particular` distillate that the limits of such distillation rangeare those included in the every day, or commercial Government or A. P.I. specifications.

It will be noted that, while certain4 of the described steps have beenshown as batch operagenous bases in the original raw distillate ispreferably accomplished as an initial step of the process, such removalmay be effected at any .time prior to, or as far as the nitrogen basesare concerned, during the initial step of subsequent treatment withstrong sulphuric acid.

The SO2 extract-may therefore be treated with caustic solution for theremoval of organic acids at any time prior to treatment withconcentrated sulphuric acid.

'Likewise if the son extract is met treated with.V

caustic soda solution and then treated with concentrated sulphuric acidin relatively small vol'l ume. as described, so as only to eiect sulphurremoval with low sulphonation of aromatica, the

extract will then be free of nitrogenous'bases because they will beremoved by the concentrated acid and also be free of organic acids andthus,

`will be in a condition suitable for use, or for sulphonatlon to yieldpure aromatica.

It is\apparent that by'suitable variations of the treatments withconcentrated sulphuric acid with regard to time of contact, temperatureof .con-

tact,- method of contact, quantity of acids, concentration of acid, theextract can be modined toyield products suitable for the u sesenumerated and that such products may yieldvarious types of aromatics.

. For instance, if the extract is treated Yhlvith acid in a plurality ofsteps including a first step with a small quantity of acid, thearomatic's most -readily attacked by acid can be extracted first andsuccessive variations of treatment can be used to provide pure aromaticsof desired vcharacteristics. Such treatment by selective reactivity ofsulphuric acid accomplishes partial sep aration without distillation.`

treatment of light distillates.

' lng application Serial No. 134,020, iiledv March' .tions for the sakeof simplicity, many of the same may bel carried on in well knowncontinuous operations and therefore suchdescrlptive operations impose`no limitations beyond the scope of the appended claims.

Although the above inventions have been dlrected towards the processingof'distillates and the recovery of valuable by-products therefrom, itshould be understood that we also include the refinement of those lightand heavy crudes containing substantial quantities of non-hydrocarbonsheretofore defined. Certain California Crudes such as those originatingfrom the Ventura, Southern California, Kettleman Hillsand Belridgeiields contain appreciable quantities of non-hydrocarbons and/orunsaturated `and aromatic hydrocarbons which are desirable sources ofby-products. Depending on the nature of the crude and the particular'by-product recovery desired distillation may be first used to greateradvantage in the later stages of processing ,and

this mode of operation is also claimed, utilizing the inventions fullydescribed for the preferred This application isl a division of ourco-pend- 6 tract to recover a desired light fraction therefrom, andtreating such light fraction. `with sulphuric acid of suicientconcentration and in an amount up to 100% by volume oi the fraction toremove aromatica, sulphur' com-pounds and unsaturates and leave theremaining oil oil high naphthene content after the removal oi* acidsludge.

2. The process of preparing solvents which comprises: removingnon-hydrocarbons like organic acids, sulphur compounds and nitrogenbases from a distillate of petroleum oil contalm' vamount up to.1 00% byvolume of the fraction to '20 naphthene content after the removal ofacid sludge.

3. The process of preparing solvents which comprises: removingnon-hydrocarbons like orgame' acids, sulphur compounds and nitrogen f efrom a distillate of petroleum oil containing aromatica, treating' thethus puried oil with a selective solvent to remove an extract therefromcontaining mainly naphthenic, unsaturated and aromatic hydrocarbons. andtreating such extract with sulphuric acid of sumcient concentration andin an amount up to 100% by volume of the fraction to remove aromatics.sulphur compounds and unsaturates and leave the rel maining oil of highnaphthene content after the removal of acid sludge.

'THOMAS F. MCCORMICK.

